As a hypnotist who's conducted many past life regressions, I can say that there's far more to our existence than a mere 72-100 years. There are many books detailing peoples' experiences of having died and then revived. These are almost all remarkably similar. Their experiences are also similar to what people describe when I guide them to "pass through the death experience." Moreover, if you were to read descriptions of heaven as told by gurus/monks in India, by psychics such as Edgar Cayce, and other spiritual adepts, they ALSO detail similar post-life experiences.
And what are those? I've had many people sit across from me during a deep hypnotic state and beam with pleasure, cry with happiness, gasp with joy - almost all saying that it's so beautiful, so amazing that words can't possibly describe it. The interesting thing is that this post-life "world" is reflective upon the individual's idea of what heaven would be. A singer heard - and felt and saw - music. A devout Christian described angels. An artist could paint with his mind and emotions. Beyond that, it's more than just eternal bliss.
Many have described, once they've passed through this initial heavenly experience, how their work is not done, how, while in this angelic/etheric realm, they can choose to help or guide those on Earth or they can move on to other planets or dimensions. Edgar Cayce specifically detailed various star systems and how those are where we as spiritual beings evolve to. (Remember, the universe is vast beyond human comprehension.)
Regarding 2012... if enough people get it in their heads that a dramatic change will occur, then it will. But don't expect cataclysm. Instead, expect a very subtle spiritual mindset change in humanity that will only be noticed upon decades-later reflection.